1. Field of Invention
The present invention relates to an illuminating technology. More particularly, the present invention relates to a structure of an illuminating unit and a structure of an illuminating light source.
2. Description of Related Art
The artificial light source is a product always widely needed in our daily life, and, for example, is used to illuminate an object or an environment without the sun light, and further the image can be projected onto a screen for viewing by people and so on. As the development of scientific technology, the illuminating technology has been accordingly developed.
For example, the light source applied in a projector is provided by a high-illumination light lamp, such as UHP, through a short arc by electric discharge. Then, the radiant lights are led into a parallel beam as the collimating light by a parabolic reflection cup. Then, two sets of lens array are used to fully mix the light, and then the mixed light is controlled by a light valve to project onto a large screen with sufficiently good image quality.
In addition, the light emitted from the emitting diode (LED) as the light source is distributed in full solid angle, and the intensity of emitted light is not uniform on each side, caused by the non-uniform distribution of the internal current density. Further, the surface of the electrode also blocks the light, and clearly causes a light-emitting device with non-uniform luminance. Furthermore, it is quite difficult to effectively lead the lights emitted in solid angle into a parallel beam as the collimating light. Therefore, it is a big challenge to have a light source with high illuminating power, collimating, and uniform light. In order to improve the illuminating condition, a conventional design is shown in FIG. 1.
FIG. 1 is a drawing, schematically illustrating the conventional structure of a light source. This conventional structure uses several bullet-shape light lamps 121 in T1 specification with a diameter size of 3 mm or 5 mm, so as to form a rectangular array 120. At the light-emitting side, in order to mix each of the non-uniform light lamps, a reflection part 110 is implemented by composing four reflective surfaces 111 into a tube structure. By the reflection effect from the reflective surface 111, the non-uniform light can be mixed at a certain level. However, each of the light lamps has a non-uniform distribution of light intensity, symmetrical to a center axis. In addition, it has a gap region without light between the four adjacent light lamps 121. This would severely cause a dark region and then a non-uniform light source with interleave between bright region and dark region. In other words, even though the tube reflection structure is used, the mixing effect is still poor.
Another conventional design is shown in FIG. 2, in which the light sources 122a, 122b are composed of several LEDs being densely close, so as to obtain the larger light-flux by driving with high current. Further, the parabolic reflective surfaces 124a, 124b are used to lead the lights in all directions into collimating light in parallel direction. In this situation, the dense LEDs driven by high current would cause a high temperature, which further reduces the light-emitting efficiency. The lights from LEDs are not uniform, and the light source is still non-uniform after passing the axial symmetric reflection mirror for collimating the light.
The foregoing conventional designs still have the disadvantages, such as non-uniform light intensity or affecting quality of light source due to high temperature. Developments are continuously made by the manufacturers for designing a better light source.